Functionalized Chitosan Biopolymer Beads for Heavy Metal Ion Removal from Mining Acid Drainage

Abstract

Mining acid drainage contains elevated concentrations of toxic heavy metal ions and acidic contaminants that pose severe environmental and ecological risks to surrounding water resources and soil systems. This study investigates the development of functionalized chitosan biopolymer beads for efficient heavy metal ion removal from mining acid drainage under varying treatment conditions. The proposed adsorbent system utilizes chitosan-based biopolymer matrices modified with functional surface groups to enhance adsorption capacity, selectivity, mechanical stability, and chemical resistance during wastewater treatment applications. A comprehensive experimental investigation was conducted to evaluate the influence of bead composition, functionalization method, pH, contact time, initial metal ion concentration, temperature, and adsorbent dosage on removal efficiency and adsorption kinetics. Advanced characterization techniques confirmed the formation of porous and chemically stable biopolymer bead structures with enhanced active binding sites suitable for adsorption of toxic metals such as lead, cadmium, copper, chromium, and zinc. Performance evaluation demonstrated significant improvements in heavy metal removal efficiency, adsorption capacity, and operational stability compared to unmodified chitosan materials. The functionalized beads also exhibited favorable regeneration characteristics and maintained adsorption performance during repeated treatment cycles. Comparative analysis revealed that optimized surface modification substantially enhances metal ion binding through electrostatic interaction, chelation, and ion exchange mechanisms.